By-pass-valve construction



oct .16, 1928.

P.\L. scoT'r BY-PASS VALVE CONSTRUCTION 'Paisted oct. 16, 192s.

UNITED STATES ,PATENT OFFICE.

PHILIP LANE SCOTT, OF CHICAGO, ILLINOIS, ASSIGNOR TO SUPER-:DIESEL TRACTOR CORPORATION, 0F LA PORTE, INDIANA, A CORPORATION OF NEW YORK.

BY-PASS-VALVE CONSTRUCTION.

Application led September 22, 1921.

My invention relates to by-pass valves used to regulate the quantity of liquid supplied in liquid pumps, particularly of the type used in supplying fuel to injection engines.

The system here described is particularly designed for injection engines employing the so-called solid or direct injection. system and in which the timing of the injection is controlled by the fuel pump. Where the timing of the discharge from the fuel pump is of little or no importance as with an air injection systemv ora mechanically operated and timed injection valve, and also with some types of engines employing hot bulbs or plates, the system here described is no advantage, but it is usually desirable and often necessary with direct injection and an automatic valve to maintain the timing` of the injection into the cylinder fixed as to its commencement. My device provides a valve needing but a very light operating mechanism which will permit the injection to begin always at the same point and which will later on in the pump stroke open and permit-the remainder of the fuel charge to be returned to the fuel supply system. y

By-pass valves are used in fuel pumps which supply a fixed quantity of fuel for each stroke where it is desired to inject a varying quantity of fuel corresponding to the load on the engine. Such by-pass valves are provided in order that the portion of the quantity pumped which is not requiredpby the engine, may be returned to the fuel supply system.

As generally known such by-pass valves have opened inward against the pressure in the pump chamber. Such inwardly opening valves must for obvious structural reasons be of considerably larger diameter than outward opening valves, because the inward opening valve exposes a diameter at least equal tothe larger seat diameter, and the smaller seat diameter must be large enough to permit the passage of a substantialstem.

Such valves are always of the poppet valve type. lVith an outward opening valve, however, only the smaller seat diameter is exposed` and this smaller seat diameter may be considerably reduced in proportion to the other type, since no stem is required to pass through this area.

A further disadvantage of inward Opening Serial No. 502,542.

valves is that. they must be opened against 'the pressure in the vpump chamber. Since the surface of the valve is necessarily oomparatively large as aboveA explained, the total load upon it and consequently upon the operating wherein the linkage which operates the valve there is a variable member which controls the quantities by-passed. This member is usually governor operated, and where this is the case the governor is necessarily very heavily load-` ed, even though there bev reductions both in the vvalve operating mechanism and in the linkage connecting the variable member with the governor. Since it is well recognized that the load on the governor should be kept as light as possible to avoid irregular and inaccurate action it is obvious that a mechanism which places a heavy load on the governor is undesirable.

One of the objects of my invention is to free the governor as completely as possible from any load. With this end in view, I have provided an outwardly opening by-pass valve of the needle type. In mv construction the valve is seated outslde of the pressure cham' ber of the pump and only the small needle 7 point is subjected to the pressure within the pump. With an outwardly opening valve the minor seat diameter may be as small as usable oil velocities permit; A pump in which the inward opening type of valve is used might have a major seat diameter of 3A; of an inch with reasonable design, whereas the outward opening valve for the same pump need only have a minor seat diameter of ,la inch to permit free passage of the oil. With a diameter of ,16 of an inch and 5000 pound injection pressure, the load on the valve will be only 15 pounds in contrast to 550 pounds for the inward opening type.

My invention is illustrated more or less diagrammatically in the accompanying drawings, wheren Figure 1 is a vertical cross section;

Figure 2 is a plan view with parts in section;

Figure 3 is a cross section on line 3 3 Qf.- Fig. l;

Figure 4 is an enlarged detail of the by-pass valve.

Like parts are designated by like characters throughout. y

A is a pump housing enlarged at one end as at A and provided with the bore A2 within which the slider B is adapted to `reciprocate.y Thisslider is hollow as at B and is closed at one end as shown. It is provided at its closed end with the roller B2 which is pivoted therein. C is a cam shaft on end of which extends into tho hollow A of the pump housing A. Mounted on the cam shaft C is the cam C which is adapted to work against the roller B2. Adjacent the cam C is the eccentric C2 about which is the eccentric strap C3 which carries the ear C1 in which is lvoted one end of the lever D, the other end) of which is pivoted in the housing at D as shown.

Within the bore B of the slider B is fixed the rod E which has at its inner end the enlarged portion E. Fixed about the rod E is the retainer E2 which is perforated as at E3 and has the enlargement E4 at its inner end.

F is the pump body fixed to the pump housing A and within yit a liner F is also iixed. The spring E5 surrounds the retainer E2 and bears at one end upon the enlarged portion E4 and at the other end upon the pump body.

is a pump plunger adapted to reciprocate within the liner F and ,extending through the perforation E3 in the spring retainer E2. It has the enlarged head G which lies within the spring retainerl and in contact with the rod E. F2 is a pump chamber within the liner F. Communicating with this pump chamber is an inlet H which is normally closed by the valve H which is opened in opposition to the spring H2 by the suction within the pump chamber. Communieating also with the pump chamber is the outlet I which is normally closed by the valve I which is adapted to be opened in opposition to the spring I2 by pressure within the pump chamber. When the valve is so opened, fuel is discharged through the valve and through the fuel line I3.

Communicating/with the pump chamber is the by-pass J adapted normally to be closed by the by-pass valve J The valve is normally seated by means of the spring J 2 which surrounds the separated valve stem J3. This stem has upon it the venlargement J 4 and is adapted at one end to slide within the guide J5. The spring J2 bears against the enlargement J4 and the guide J5. The valve stem J 3 is separate from the valve and is normally in contact with it. It is reduced at its inner end as at J 5, and surrounding this sition to the reduced portion is a spring J 7 which on the suction stroke aids the prompt seating of the Valve irrespective of the position of the separated valve stem.

Pivoted mid-Way between the lever D is the link K which is attached to the push rod K. This rod carries in its outer end the wedge K2. K2 is a second push rod which carries in its inner end the block K4. At the outer endof the push rod K3 is adjustably iixed the bracket 1'5. K is the driving spring about the shaft K3.

is a -rod connected by any suitable linkage with the governor and adapted to be moved in and out by the saine. The details of this construct-ion are not her-e shown as they form no part of the present invention. Mounted on the end of the rod L is a wedge L. This wedge as shown is contacted by the wedge K2 of the block K2.. In accordance with its position as it is moved in and out by the governor, the length of the linkage from the lever D to the block K2 is varied and the time at which the bracket K5 contacts with the enlargement J t is varied, thus changing the time at which the valve J opens and varying the time in the pump stroke at which discharge to the injection valve ceases and discharge through the valve J commences to the fuel tank.

The use and operation of this invention are as follows:

With the rotation of the cam shaft the push rod is reciprocated, the total length of the push rod linkage being varied by the movement of the wedge which is controlled by the governor.

The action of the push rod assembly is as follows: During the outward reciprocation of the two push rods, the bracket on the outer ,one contacts the collar on the separated valve stem and so moves it outward in opposition to the spring which surrounds the valve stem.

This movement of the valve stem frees the valve which is then forced from its seat by the pressure in the pump chamber, thel bypass being thereby opened'. In the opening of the valve the effect of the small spring which surrounds the reduced portion of the separated valve stem is negligible in oppopressure from the pump chamber upon the valve. As thus described the opening of the valve is entirely mechanically controlled Ibut the closing which will now be described,'is purely automatic.

Practically the moment that the pump plunger begins its return stroke, suction is substituted for the pressure within the pump chamber and this suction combined with the action of the small spring bearing againstthe valve in causing prompt closure immediately upon the commencement of the suction stroke. Subsequent to the closing of the valve the push rod assembly makes its return reciprocation to the `point wherethe larger spring is enabled to return the valve stem to the position shown in Fig. 1, and the parts are returned to this position before any pressure is built up in the pump chamber. The valve is then heldv closed against .injection pressure by the larger spring, until the moment when the above described cycle is commenced again.

Since the valve itself is separate from the comparatively large and heavy valve .stem and other operating parts, and since the small valve is automatically seated before the return movement of the valve stem, and since the valve stem and other parts may by this construction be returned gradually, prompt closing is accomplished withoutr pounding and battering, resulting from the inertia of the heavy parts. If the valve were integral with the valve stem and positively connected with the other parts of the valve operating mechanism to obtain quick closure of the valve, very rapid motion of the operating parts would be necessary, and this objectionable pounding on the seat would be greatly increased.

I claim.:

1. In combination with a pressure chamber and means for intermittently building up pressure therein, a discharge passage ther from and a by-pass discharge therefrom, a closure for the by-pass normally held against opening, opening in response to pressure in the chamber, and means for intermittently releasing said closure to permit by-pass discharge away from supply, and separate means leasing said closure to permit intermittenty by-pass discharge away from supply, said closure comprising a floating valve adapted toY close automatically upon reduction of pressure in the chamber.

3. -In combination with a pressure chamber and means for intermittently building up pressure therein, a discharge passage therefrom, and a by-pass discharge therefrom, a

4. In combination with an internal combustion engine, a liqiid pump having a pressure chamber, and a y-pass leading from said chamber, an outwardly opening valve held on its seat by. a-separate stem and being adapted to close said by-pass and to open intermittently and automatically in response to pressure from within the chamber, means for operating said valve including a reciprocating linkage eccentrically driven by said engine, a link of variable governor controlled length within said linkage.

5. In combination with an internal combustion engine, a liquid pump having a pump chamber'with a by-pass therefrom, an out- ,y

wardly opening valve held on its seat by a separate stem and yielding means' normally adapted to seat said valve and means for compressingsaid yielding means to permit said valve to be opened outwardly by pressure within said pump chamber, said means comprising a reciprocating linkage eccentrically driven by said engine and having a link of variable length therein, said valve adapted to open intermittently and automatically in response to pressure from within the chamber. A 6. In a liquid pump, a pressure chamber, a by-pass in communication therewith having a valve therein, and yielding means for normally holding said valve seated, said means comprising a reciprocating valve stem separate from and in contact with said valve, and a spring adapted normally. to hold said stem against said valve to seat same, and means for positively moving said stem out of contact with said valve whereby the valveis adapte-d to open automatically, and intermittently in response to pressure within the pressure chamfber when the -same is mechanically withdrawn.

7. In a liquid pump, a pressure chamber,

a by-pass in communication therewith having a valve therein, and yielding means for normally holding said valve seated, said means comprising a reciprocating-valve stem separate from and in contact with said valve, and a spring adapted normally to hold said stem, against said valve to seat same, and 4means for positively moving said stem out of contact with said valve, and a spring between said stem and said valve, said spring normally under pressure whereby the valve is adapted to open automatically, and intermittently in response to pressure within the pressure chamber when the same is mechanically withdrawn. i

Signed at Chicago, county of Cook and State of Illinois, this 20th day of September,

PHILIP LANE SCOTT. 

